Many people wear headphones in order to listen to a wide variety of audio, such as music, the soundtrack of a video, audio programs, e.g., podcasts, books on tape or the like. Headphones permit people to listen to audio signals in a manner that does not disturb other people and that maintains the privacy of the listener. Additionally, headphones facilitate mobility, thereby further allowing people to listen to audio signals while walking, running or performing a wide variety of other activities.
The audio quality provided by headphones may vary widely between different pairs of headphones. For example, headphones may apply gain to the different frequency bands of the audio signals in such a manner that the resulting audio signals are of lower quality than is desired. In an effort to increase the quality of the audio signals that is delivered to a listener, a multi-band equalizer could be utilized in conjunction with the headphones such that the listener could individually adjust the gain to be applied to the audio signals in each of a plurality of different frequency bands. However, a multi-band equalizer requires a listener to be relatively sophisticated with respect to audio signal tuning if the quality of the audio signals is to be meaningfully improved. In addition, a listener may have to reconfigure the gain provided by a multi-band equalizer for each of the plurality of frequency bands in instances in which the listener is going to listen to different types of audio signals or different genres of music. Indeed, equalization that depends upon the gain to be separately set for two or more distinct frequency bands, such as bass and treble, may prove challenging for a listener and may result in the listener failing to reconfigure the gain even as the type of audio signals changes, thereby resulting in lower audio quality.
Alternatively, a pair of headphones may include a simple adjustment, such as bass boost, to provide a limited modification of the audio signals. However, such a simple modification, such as bass boost, may not provide a meaningful improvement to the resulting audio signals.
The audio response of different types of headphones may be equalized using two full-band filters with the parameters of the two full-band filters being defined by principal component analysis of a set of frequency responses measured from several headphones of different sizes, such as from several small and large sized headphones, namely, by the first and second principal components. However, it may be difficult for listeners to determine the optimal point at which to set the principal components in order to provide for appropriate full-band filtering since the values of the first and second principal components are not intuitive.